The present invention relates to a server-based computing technique, and particularly to a server-based computing technique in a computer system having a client that permits offline work too.
Recently, there has been a trend toward lower prices of personal computers (PCs) and network devices, and more companies supply terminals such as PCs to most of their employees to make them do their work on their terminals. In proportion to the increase of PCs used in a company, an equipment administrator of the company should carry out the maintenance of more PCs. As such maintenance, may be mentioned, for example, upgrading and bug fixing of an operating system (OS) and business application programs, dealing with hardware failures, taking anti-virus countermeasures, and removing viruses.
The cost of such maintenance work is very large and increases in proportion to the number of PCs to be managed. Thus, even if it is possible to introduce PCs at a cheaper price, maintenance work after the introduction entails great cost.
As a method of decreasing the maintenance cost, there are server-based computing techniques such as Windows Terminal Service and citrix metaframe (See, for example, Microsoft, “Technical Overview of Terminal Services”, [online], July 2002, <URL: http://download.microsoft.com/download/2/8/1/281f4d9 4-ee89-4b21-9f9e-9accef44a743/TerminalServiceOverview. doc> (hereinafter, referred to as Non-Patent Document 1), Dan Kusnetzky, “Realization of Virtual Computing Environment Using Citrix Application Infrastructure Software”, [online], IDG Japan, Date of last retrieval 2004/02/13, < URL: http://www.citrix.co.jp/site/resources/pdf/products/IDCpaper—3511_finalQCJ.p df> (hereinafter, referred to as Non-Patent Document 2)).
The server-based computing takes the form of a client-server computing system. And, in a server-based computing system, an application program requested by a client is executed on the side of a server.
A system according to the server-based computing is provided with a computer (a server) that executes processing (application programs) that users need for their work and terminals (clients) for instructing execution of application programs to the server and for confirming the results. Through a client at hand, a user gives an instruction to the server, to which the client is connected through a network, in order to execute an application program on the server. Then, a result of the execution on the server is displayed on the screen of the client. Thus, only if a user equips a PC or portable terminal at hand with a server connecting function, then, at a location where network connection to the server can be established, the user can use the application programs in the same environment as his office and do his work.
Further, in a system according to the server-based computing, all processing functions (application programs) and all information (data) relating directly to the work are placed on the side of the server and managed by the server in a centralized way. Accordingly, on the side of a client, it is possible to restrict application programs installed on the client to the necessity minimum. Further, the application programs can be easily updated.